1. Technical Field
The present application relates to an X-ray tube.
2. Discussion of Related Art
A conventional X-ray tube includes a cathode and an anode, wherein the cathode and the anode are in a vacuum tube. The cathode could be a field emission cathode device. In particular, the carbon nanotube-based field emission cathode has attracted much attention in recent years.
A method for making field emission cathode device usually includes the steps of: providing an insulating substrate; forming a cathode electrode on the substrate; forming a dielectric layer on the cathode electrode; and depositing a plurality of carbon nanotubes on the exposed cathode electrode as the electron emitter by a chemical vapor deposition (CVD) method.
However, the plurality of carbon nanotubes fabricated by the CVD method cannot be secured on the cathode electrode. The plurality of carbon nanotubes is prone to be pulled out from the cathode electrode by a strong electric field force, thus causing the field emission cathode device to have a short lifespan, further causing the X-ray tube to have a short lifespan.
What is needed, therefore, is to provide an X-ray tube that can overcome the above-described shortcomings.